1. Field of the Invention
The present invention relates to a concentric joint mechanism, and more specifically, to a concentric joint mechanism capable of rotating with multiple degrees of freedom.
2. Description of the Prior Art
In general, a traditional robot arm capable of operating with multiple degrees of freedom utilizes a plurality of motors in a tandem manner to simulate motion of human limbs. However, the rotating axis of each motor can not point to the same axis center when the robot arm is operated. Therefore, extra torques may appear on the robot arm. In addition, disposal of the plurality of motors may occupy more space and mutual interference between motors may occur when the robot arm is operated. The said problems may make it difficult to control the robot arm smoothly. Therefore, for making control of the robot arm easier and resolving the mutual interference problem of the robot arm, an electromagnetic induction controlling method appears accordingly. Via magnetic levitation caused by electromagnetic induction, the said method allows motion of the robot arm to have multiple degrees of freedom. However, difficulty in magnetism control and mechanic calculation when an external force is exerted on the robot arm and excessive space occupied by an electromagnetic device make this method incapable of being applied to practical operation.